The region around the city of Rotorua, in New Zealand's North Island, contains several lakes. From biggest to smallest, these are Lake Rotorua (Second Lake), Lake Tarawera, Lake Rotoiti (Small Lake), Lake Rotoma (White Lake), Lake Okataina, Lake Rotoehu (Muddy Lake), Lake Rotomahana (Warm Lake), Lake Rerewhakaaitu, Lake Rotokakahi (Green Lake), Lake Okareka and Lake Tikitapu (Blue lake). There are also four smaller lakes: Lake Okaro/Ngakaro, Lake Rotokawa (not to be confused with Lake Rotokawa near Taupo), Lake Rotokawau and Lake Rotongata (Mirror Lake). Most of the lakes have formed due to volcanic activity. The region is part of the Taupo Volcanic Zone, the world's most active area of explosive silicic volcanic activity in geologically recent time. Geographic statistics Lake Rotorua Lake Rotorua is the largest of the lakes with Lake Tarawera close behind, it is also the second largest lake in the North Island by surface area and covers 79.8 square kilometers. With a main depth of only 10 metres it is smaller than Lake Tarawera by water volume. The lake lies within a large volcanic caldera in the Taupo Volcanic Zone. After an eruption, the magma chamber underneath the volcano collapsed. The depression left behind is the Rotorua Caldera. Mokoia Island, is close to the middle of the lake and is the setting for the legendary tale of Hinemoa and Tutanekai. Lake Tarawera Lake Tarawera is the second largest lake in the rotorua caldera with a surface area of 51.0 km². It is filled by sources from the nearby Blue and Green lakes (or Lake Rotokakahi and Lake Tikitapu). Lake Tarawera is home to various eels and rainbow trout. During the summer the lake is popular for both fishing and water sports, and also camping as there a number of hot water beaches. Lake Tarawera's outflow is at its north end, into the Tarawera River, which flows further into the Pacific Ocean. Lake Rotoiti Lake Rotoiti is the third largest lake in the Bay of Plenty region of New Zealand. It is the westernmost in a chain of lakes formed within the Okataina caldera. The lake is close to the northern shore of its most famous neighbour, Lake Rotorua, and is connected by the Ohau Channel. The Māori-language name "Rotoiti" means "the little lake". The lake covers an area of 38.6 square kilometres. Lake Rotoma Lake Rotoma is the fourth largest lake in the Bay of Planty region